The incidence of malignant melanoma and nonmelanoma skin cancer appears to be increasing at an alarming rate. Many cases of skin cancer could be prevented if individuals decreased their unprotected exposure to sources of ultraviolet radiation, such as sunlight and tanning lamps (primary prevention). If skin cancer does occur, early detection substantially increases the likelihood of successful treatment (secondary prevention).While primary and secondary prevention could substantially decrease the incidence of, and the morbidity and mortality from, skin cancer, neither are sufficiently practiced. To improve skin cancer prevention, messages about primary and secondary prevention practices must be effectively disseminated, one potentially appropriate avenue being in the setting where people receive their primary health care. Mass media education about skin cancer is expensive, and prevention messages are often minimized or ignored because they lack specificity. Special dermatologic screening clinics pose other dissemination problems, in that individuals who present to be screened already practice secondary prevention (i.e., have detected suspicious lesions). In contrast, if messages about primary and secondary prevention of skin cancer were incorporated into routine health care, all patients would be in a position to receive individualized advice and counseling from an authoritative and trusted source, their physician. Our study proposes to test the separate and combined effectiveness of two interventions disseminated through a primary health care setting to increase primary and secondary prevention of skin cancer. One intervention will be targeted at primary care physicians, but the other will be targeted at patients. We will assess which intervention strategy (Physician-based,Patient-based,or a combination of both) most effectively decreases patients' unprotected exposure to ultraviolet radiation; increases the frequency with which patients perform total-body self- examinations of their skin; increases the frequency with which primary care physicians counsel patients about primary prevention of skin cancer; and increases the frequency with which primary care physicians perform total-body skin examinations of their patients.